Miniaturization of a biomedical gas sensor

Abstract

In a previous study, we concluded that a conductivity based PCO2 sensor is an attractive solution for early detection of ischemia and presented two design geometries. For organ surface measurements, the planar design was suitable but it was difficult to insert the sensor into the tissue. A cylindrical design solution was favored for insertion due to the large membrane contact area and easy placement in a medical catheter. Since the previous cylindrical prototype was large and could damage the tissue, a more miniaturized sensor was needed. In the current paper, we present a miniaturized sensor with an outer diameter of 1 mm. The applied technology for manufacturing the sensor was a combination of mechanical turning, excimer laser drilling and conventional molding technique. The materials applied were PEEK (polyetherether ketone), PI (polyimide) with gold layers and polysiloxane. The membrane had to be gas permeable while acting as a barrier for ion transport, and was made of polysiloxane and had a thickness of 100-150 microm. The miniaturized sensor was tested for calibration, response time, drifting and pressure sensitivity. The results show that the miniaturized PCO2 sensor is capable of rapid and stable measurements both in vitro and ex vivo. The result from this study will be applied for the industrial manufacturing of such a biomedical sensor as a clinical product.

Hepatic and Abdominal Carbon Dioxide Measurements Detect and Distinguish Hepatic Artery Occlusion and Portal Vein Occlusion in Pigs

“…IscAlert sensors detect changes in PCO 2 from an automatically calculated baseline at zero based on a conductometric method described elsewhere. 18 Briefly, a gas-permeable membrane allows tissue carbon dioxide (CO 2 ) diffusion into the water-filled sensor, in which CO 2 dissolves into HCO 3…”

Tissue gas tensions and tissue metabolites for detection of organ hypoperfusion and ischemia

“…Microdialysis is a clinically available technology that can be used in muscle and abdominal organs such as the liver and intestine to detect ischemia . There are also emerging clinical technologies for real‐time measurement of PCO 2 in muscle and internal organs . The majority of PCO 2 studies have been carried out in different parts of the gastrointestinal tract, mainly stomach, and less is known about PCO 2 in solid organs during hemorrhagic shock .…”

Trends in Electrochemical Sensing of Blood Gases

“…10). Studies by the same group [34] resulted in a miniaturized cylindrically shaped cell configuration. They have presented an ex vivo measurement in a small latissimus dorsi muscle flap of a pig.…”